Design Considerations Based on Stability for a Class of TCP Algorithms

TL;DR

This paper analyzes the stability of various TCP algorithms using fluid models, deriving scalable conditions that ensure stable operation across different network topologies and buffer regimes.

Contribution

It formulates new stability conditions for a class of TCP algorithms considering heterogeneous delays and small buffers, applicable to diverse network configurations.

Findings

Derived sufficient stability conditions for TCP variants.

Conditions are scalable across various network topologies.

Small buffer regimes enable decentralized stability considerations.

Abstract

Transmission Control Protocol (TCP) continues to be the dominant transport protocol on the Internet. The stability of fluid models has been a key consideration in the design of TCP and the performance evaluation of TCP algorithms. Based on local stability analysis, we formulate some design considerations for a class of TCP algorithms. We begin with deriving sufficient conditions for the local stability of a generalized TCP algorithm in the presence of heterogeneous round-trip delays. Within this generalized model, we consider three specific variants of TCP: TCP Reno, Compound TCP, and Scalable TCP. The sufficient conditions we derive are scalable across network topologies with one, two, and many bottleneck links. We are interested in networks with intermediate and small drop-tail buffers as they offer smaller queuing delays. The small buffer regime is more attractive as the conditions for stability are decentralized. TCP algorithms that follow our design considerations can provide stable operation on any network topology, irrespective of the number of bottleneck links or delays in the network.